Condensate Oscillations, Kinetic Equations and Two-Fluid Hydrodynamics in a Bose Gas
Abstract
This is based on 4 lectures given at the 13th Australian Physics Summer School, Australia National University, Canberra, Jan 17-28, 2000. The main topic is the theory of collective modes in a trapped Bose gas at finite temperatures. A generalized Gross-Pitaevskii equation is derived at finite temperatures, which is used to discuss a new mechanism for damping in the collisionless region arising from interactions with a static thermal cloud of non-condensate atoms. Next, introducing a kinetic equation for the thermal cloud, we derive two-fluid equations of motion for the condensate and non-condensate components in the collision-dominated hydrodynamic region. We show that these are precisely the equivalent of the Landau two-fluid equations in the limit that the two components are in diffusive local equilibrium. However, our equations also predict the existence of a new zero frequency relaxational mode, in addition to the usual Landau hydrodynamic modes (such as first and second sound). The special importance and simplicity of two-fluid hydrodynamics is stressed.
Keywords
Cite
@article{arxiv.cond-mat/0006382,
title = {Condensate Oscillations, Kinetic Equations and Two-Fluid Hydrodynamics in a Bose Gas},
author = {Allan Griffin},
journal= {arXiv preprint arXiv:cond-mat/0006382},
year = {2015}
}
Comments
50 pages, 7 figures; To appear in "Proceedings of the 13th Physics Summer S chool: Bose-Einstein Condensation", eds. C.M.Savage and M.Das (World Scientific, 2000)